Answer:
6x+9
Step-by-step explanation:
A) The first step needs 100 bricks, the second needs 98, the third needs 96, and so on. Therefore the number of bricks for the nth step is: a_n = a_1 + d(n-1), where a_1 = 100 (the first term), d = -2 (difference).
a_n = 100 - 2(n-1) = 102 - 2n, and for the 30th step, a_30 = 102 - 2*30 = 42. So the top step will need 42 bricks.
b) The total staircase will need: 100 + 98 + 96 + ... + 44 + 42, and there are n = 30 terms. Using the formula for the sum of an arithmetic sequence:
S = (a_1 + a_n)*n/2 = (100 + 42)*30/2 = 2130
Therefore, 2130 bricks are required to build the entire staircase.
Answer:
X < -9
Step-by-step explanation:
5a +18 < -27
5a < -27 -18
5a < - 45
5a/5 < - 45/5
a < - 9
Answred by Gauthmath
5000 pounds is equal to 2.5 tons because 1 ton is equal to 2000 pounds
Answer:
3
Step-by-step explanation:
It's given that ΔDEF ∼ΔXYZ . So the corresponding sides of both triangles will be proportional to each other.
DE = 4 ; XY = 4(n + 1) ; EF = 5 ; YZ = 7n - 1
Putting all these values gives ,
